Instead we now recommend naming packages flask_foo instead of the now deprecated flaskext.foo. Flask 0.8 introduces a redirect import system that lets uses import from flask.ext.foo and it will try flask_foo first and if that fails flaskext.foo.

Flask extensions should urge users to import from flask.ext.foo instead of flask_foo or flaskext_foo so that extensions can transition to the new package name without affecting users. (Source)

Use this import way with Flask 0.8 or later:

from flask.ext.login import LoginManager

Email codedump link for New to flask and Flask-Login - ImportError: No module named login